When Catherine Kennedy returned to Herschel Island in 1998, she started to think that she had made a major mistake when working there thirteen years earlier. A botanist with the Yukon Government, Kennedy had mapped the island's vegetation back in 1985, just before it was established as a territorial park.

At that time almost half of the island had been covered with typical arctic plants such as willows and dryas. But now, all across the island she saw lots of grass; a knee-high coarse grass that she did not remember as being so abundant on her last visit.

Kennedy was training the park rangers on Herschel to recognize key plant species on the island, and this grass, Arctagrostis latifolia, was not supposed to be a major species there according to her notes.

But Kennedy went back to her data and photos from her previous work, and saw that the grass had indeed grown there before, though you had to look very hard to find it.

"It is so massive a change," she said. "It really looks like a grazing landscape now."

The grass was not the only surprise. Herschel has often been described as a natural flower garden, exploding with colour in the summer, but Kennedy says that the intense blue of the lupines really stood out on her return visit.

The lupines were still growing in the same sorts of sites where Kennedy had mapped them before; they were just larger and more abundant now. The grass, on the other hand, was proving to be a very aggressive invader.

Not only was it taking over the bare ground found in frost boils, it was also pushing its way into stable climax communities, the type of vegetation that usually does not give up ground easily once it has established itself. In all the grass had increased ten-fold, from 1 percent back in 1985 to more than 10 percent today.

There have also been changes with the wildlife on Herschel. Caribou have always been regular visitors there, swimming over from the mainland or crossing on the ice, but now musk oxen are making the trip as well.

Dorothy Cooley, a regional biologist with the Yukon Government, wants to figure out what the animals are eating, and the park rangers are helping with this work. They have been recording wildlife sightings since 1987, and now they are also noting the types of vegetation in areas where the musk oxen and caribou spend time.

No doubt the soil conditions have had a lot to do with the flourishing grass and lupines. Scott Smith, a permafrost researcher working on Herschel, suspects that the soil might be drier now than it was in the past. He remembers seeing the particular grass now flourishing on Herschel in Siberia, another dry area, where it was grown as a feed crop for cattle.

Frost boils used to be a dominant feature on the island's uplands, as well as a sure sign that lots of permafrost action was taking place in the ground. But now that grass is taking root in these once-bare areas, it seems likely that the soils are not churning as much as they used to in the past.

While it is not unusual for frost action to vary in an area, Smith says that changes usually takes place over the span of hundreds of years, not a decade or two. To monitor what is happening, he has placed temperature sensors in holes bored into the permafrost, both in the active layer near the surface and deeper down. The project is part of the International Tundra Experiment (ITEX), which has sites around the circumpolar North.

"Permafrost is a good material for looking at environmental change," says Smith, explaining that temperature changes below the active layer reflect changes in the mean annual temperature.

Smith chooses his words carefully when saying that they are looking at environmental change, not climate change.

"I do have an underlying suspicion that it is climate change, but I do not want to say that yet as there could be other influences."

Herschel has no bedrock. Forty thousand years ago glaciers flowing out of the Mackenzie Delta piled up the marine sediments that form the island. Now the rate at which those soils are slumping back into the Arctic Ocean also seems to be increasing.

"My casual observation is that there seems to be a tremendous amount of thaw on the north side of the island. Thaw had always been taking place there, but there seems to have been more of it last summer, and this would be consistent with observations made in Tuktoyaktuk and other locations," says Smith.

All of the researchers say that it is too early to know whether the changes being observed on Herschel are just part of a natural fluctuation. Maybe 1,000 years ago the tundra on Herschel also resembled a pasture in the prairies.

For them, the bigger question is whether similar changes are happening in other spots across the North, and if so, what that will mean for the animals that live there.

Catherine Kennedy can be reached by phone at 667-5407 or by e-mail at catherine.kennedy@gov.yk.ca. Scott Smith's e-mail address is smithcas@em.agr.ca.